The invention relates to a three piece tire with a removable tread belt mounted on a reinforced tire carcass. One use of the invention is typically for use with earthmoving vehicles, others include any application where dual wheel assemblies are commonly employed.
The three piece tire assembly of the present invention are generally designed for use on earthmover vehicles and are subjected to high stress and loads under harsh environmental conditions such as in rock quarries, mines, foundries, and other areas where tires are subjected to puncture-producing and wear-inducing conditions.
As discussed in U.S. Pat. No. 4,351,380, certain prior art tread belt tire assemblies comprise a plurality of ground engaging shoes spaced about the periphery of the supporting structure. The heavy loads on the shoes result in great stresses being developed that sometimes lead to premature tire failure. The U.S. Pat. No. 4,351,380 is directed to an improved track belt assembly which comprise a plurality of shoes spaced about the periphery of a load-supporting structure and secured to a reinforcing belt structure disposed on the side of the shoe opposite the ground-engaging side thereof.
The large pneumatic tires, which are typically used for earthmoving vehicles, sometimes fail due to the high stress and loads caused by the harsh environmental conditions in which they are operated. These large prior art pneumatic tires had a greater tendency to fail in the crown or shoulder area of the tire due to excessive heat build up.
In the prior art, conventional solutions to these problems include increasing the robustness, and decreasing the tire deformation under load by increasing the sidewall stiffness. To further improve tire durability, the ply turn-up portion of these tires was typically reinforced.
With the continual drive to improve earthmover performance to severe continuous service conditions requiring 20 hours and up of service per day, seven days a week, there is a continuing need to provide novel methods and tire designs for improving earthmover tire durability. The present invention is directed to an improved pneumatic tire carcass and removable tread belt assembly with which the frequency of premature tire failure is thought to be substantially reduced. The present invention is also directed to providing an improved three piece tire assembly, which is designed to operate at long hours without damaging heat buildup. Moreover, the present invention relates to an improved three piece pneumatic tire wherein a removable tread belt and carcass assembly can replace conventional dual tires on any dual axle assembly including trucks, tractors, light truck vehicles, and trailers.
A three piece tire assembly has a pair of tires and one removable tread belt. The tread belt encircles and annularly contacts the circumference of both tires. The pair of tires is coaxially aligned when mounted on rims. The rims preferably are laterally spaced dual rims commonly found on trucks and heavy earthmoving type vehicles. The rims are rigidly attached when the tires are mounted. The tires are preferably radially expandable. The tires of one embodiment of the invention are pneumatic. The tires can be provided without a ground engaging tread and without a belt reinforcing structure. Preferably the tires have at least one carcass ply. The removable tread belt is preferably a circular elastomeric cord reinforced ring that is placed in tension when the pair of coaxially aligned tires are inflated. Alternatively, the removable tread belt can be made as a flat track having ends. The ends, when joined, form a circular elastomeric cord reinforced ring. The tread belt has an inner surface, the inner surface has one or more radially inwardly projecting restraining elements laterally in contact with at least one tire.
The three-piece tire has the one or more restraining elements being a single rib or a plurality of ribs or circumferentially aligned lugs positioned between the tread belt and the two tires. In another embodiment the tread belt has a plurality of restraining elements formed by a plurality of grooves and tread elements wherein at least one of the tires has a circumferentially outer surface tread having tread elements and grooves that interlock with complimentary restraining elements of the tread belt when assembled.
In another embodiment, the tread belt has a radially inner surface having a restraining groove and one or more restraining elements as a separate component positioned between the two tires and projecting into the restraining groove of the tread belt.
The removable cord reinforced elastomeric tread belt has a radially outer tread, a belt reinforcing structure radially inward of the tread, and a radially inner surface wherein the radially inner surface has a lateral width sufficient to encircle two tires for normal dual wheel axles. The radially inner surface of the tread belt has one or more restraining elements to prevent the tread belt from slipping off the two tires when mounted.
xe2x80x9cApexxe2x80x9d means a non-reinforced elastomer positioned radially above a bead core.
xe2x80x9cAspect ratioxe2x80x9d of the tire means the ratio of its section height (SH) to its section width (SW) multiplied by 100% for expression as a percentage.
xe2x80x9cAxialxe2x80x9d and xe2x80x9caxiallyxe2x80x9d means lines or directions that are parallel to the axis of rotation of the tire.
xe2x80x9cBeadxe2x80x9d means that part of the tie comprising an annular tensile member wrapped by the ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes, toe guards and chafers, to fit the design rim.
xe2x80x9cBelt or breaker reinforcing structurexe2x80x9d means at least two layers of plies of parallel cords, woven or unwoven, underlying the tread, unanchored to the bead, and having both left and right cord angles in the range from 17xc2x0 to 75xc2x0 with respect to the equatorial plane of the tire.
xe2x80x9cBias ply tirexe2x80x9d means a tire having a carcass with reinforcing cords in the carcass ply extending diagonally across the tire from bead core to bead core at about 25xc2x0-50xc2x0 angle with respect to the equatorial plane of the tire. Cords run at opposite angles in alternate layers.
xe2x80x9cCircumferentialxe2x80x9d means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction.
xe2x80x9cChafersxe2x80x9d refers to narrow strips of material placed around the outside of the bead to protect cord plies from degradation and chaffing caused by movement of the rim against the tire.
xe2x80x9cChippersxe2x80x9d means a reinforcement structure located in the bead portion of the tire.
xe2x80x9cCordxe2x80x9d means one of the reinforcement strands of which the plies in the tire are comprised.
xe2x80x9cEquatorial plane (EP)xe2x80x9d means the plane perpendicular to the tire""s axis of rotation and passing through the center of its tread.
xe2x80x9cFlipperxe2x80x9d means a reinforced fabric wrapped about the bead core and apex.
xe2x80x9cFootprintxe2x80x9d means the contact patch or area of contact o the tire tread with a flat surface under load and pressure.
xe2x80x9cInner linerxe2x80x9d means the layer or layers of elastomer or other material that form the inside surface of a tubeless tire and that contain the inflating gas or fluid within the tire.
xe2x80x9cNet-to-gross ratioxe2x80x9d means the ratio of the tire tread rubber that makes contact with the road surface while in the footprint, divided by the area of the tread in the footprint, including non-contacting portions such as grooves.
xe2x80x9cNominal rim diameterxe2x80x9d means the diameter of the rim base at the location where the bead of the tire seals.
xe2x80x9cNormal inflation pressurexe2x80x9d refers to the specific design inflation pressure at a specific load assigned by the appropriate standards organization for the service condition for the tire.
xe2x80x9cNormal loadxe2x80x9d refers to the specific load at a specific design inflation pressure assigned by the appropriate standards organization for the service condition for the tire.
xe2x80x9cPlyxe2x80x9d means a continuous layer of rubber-coated parallel cords.
xe2x80x9cRadialxe2x80x9d and xe2x80x9cradiallyxe2x80x9d mean directions extending radially toward or away from the axis of rotation of the tire.
xe2x80x9cRadial-ply tirexe2x80x9d means a pneumatic tire in which the ply cords, which extend from bead to bead are laid at cord angles between 65xc2x0 and 90xc2x0 with respect to the equatorial plane of the tire.
xe2x80x9cSection height (SH)xe2x80x9d means the radial distance from the nominal rim diameter to the outer diameter of the tire at its equatorial plane.